In a large pot, combine 8 cups of chicken broth, ½ cup of fresh lemon juice, 1 cup of shredded carrots, 1 finely chopped onion, ½ cup of finely chopped celery, 2 tablespoons of chicken soup base, and ½ teaspoon of ground white pepper. Bring this vibrant mixture to a boil over medium-high heat, then reduce to a simmer for 15-20 minutes until vegetables are tender.

In a small bowl, mix 2 tablespoons of margarine with 2 tablespoons of all-purpose flour until it forms a smooth paste. Gradually stir this mixture into the simmering soup, allowing it to thicken for about 8-10 minutes on low heat.

In a separate bowl, whisk together 4 egg yolks, then temper them by slowly drizzling in 1 cup of hot soup while whisking continuously. Stir this tempered mixture back into the pot, keeping the heat low to avoid boiling.

Add 1 cup of cooked white rice and 2 cups of diced cooked chicken to the pot, stirring gently. Heat through for about 5 minutes on low heat.

Ladle the soup into bowls and garnish each with fresh lemon slices before serving warm.